[op25-dev] OP25 for noobs by a noob (long)

'William Becks' wa8wg@centurytel.net [op25-dev] op25-dev at yahoogroups.com
Fri Sep 1 03:47:46 UTC 2017



Be sure to add the following to your OP25 scope.py configuration….


sudo nano /etc/modprobe.d/dvb-blacklist.conf     (This is needed to support the RTL2832U type SDR.)

blacklist r820t
;blacklist rtl2832
blacklist rtl2830
blacklist dvb_usb_rtl28xxu

ctrl+x to save and exit


The following is generally needed when running GNU Radio + OP25 SCOPE.PY under Ubuntu 14.04 in VirtualBox to prevent audio stutter.


NOTE*  You’ll have to sudo alsamixer to set Master/PCM audio mixer controls as this operation removes the Ubuntu Desktop volume control.   Hit ESC to exit the mixer panel then follow with sudo alsactl store to make permanent.  You still need to set the volume slider control in scope as desired.


sudo cp /etc/pulse/client.conf /etc/pulse/client.confbackup
sudo nano /etc/pulse/client.conf
Edit the following line: From: ; autospawn = yes To: autospawn = no

ctrl+x to save and exit



One last point.   If running in VirtualBox, set your Ubuntu virtual machine setting for USB3.0 support, else stutter audio stutter or failure to decode P25 frames error free.

Once you get scope working you may want to consider going with the MAX Branch of OP25 (rx.py) instead of scope as it’s easy to setup in a headless configuration that you can have auto start with an entry in /etc/rc.local for example…







From: op25-dev at yahoogroups.com [mailto:op25-dev at yahoogroups.com] 
Sent: Wednesday, August 30, 2017 3:30 PM
To: op25-dev at yahoogroups.com
Subject: Re: [op25-dev] OP25 for noobs by a noob (long)



Okay, i went ahead and bought a 0.5 PPM TCXO NESDR SMArt device and am going to start over from the beginning. And Bill, it

was only $25 and I as a kit it included the NESDR SMArt, an external antenna stand with three options of antennas. Will update you

once I get this all done again. Also, someone was experimenting with using wireshark, once I can hear something I'll look at that as

I spent way too much time digging around the kernel with the Hackrf....but, still determined to win that one too. Thanks all for your

help and discussions. 


Beam me up Scotty.....



From: "'WA8WG' wa8wg at centurytel.net [op25-dev]" <op25-dev at yahoogroups.com>
To: op25-dev at yahoogroups.com 
Sent: Thursday, August 10, 2017 10:06 AM
Subject: RE: [op25-dev] OP25 for noobs by a noob (long)



I stand corrected.  You will see the NAC provided you don’t have –v (n) specified on your scope.py command line.   Just execute your scope.py or scope.sh from a terminal command prompt and watch the top of the text output as scope.py starts and you’ll see the NAC with the -T trunk.tsv omitted.   





From: op25-dev at yahoogroups.com [mailto:op25-dev at yahoogroups.com] 
Sent: Thursday, August 10, 2017 7:39 AM
To: op25-dev at yahoogroups.com
Subject: Re: [op25-dev] OP25 for noobs by a noob (long)



As was also suggested before, running scope.py without the -T argument on the control channel will show the NAC using no additinal hardware than what you already have, including no reason whatsoever to use a separate Windows computer.


On Aug 9, 2017 19:42, "wa8wg at centurytel.net [op25-dev]" <op25-dev at yahoogroups.com> wrote:




I was going to suggest that your try setting the NAC in trunk.tsv to 0xF7E that is a universal NAC that works

to decode any P25 system when programmed in a Motorola P25 radio but I tried it with scope.py and got

no system audio until I put the correct NAC back in my trunk.tsv.      So I am thinking that your remaining issue is likely that you have the wrong NAC and should try to follow my suggestions to obtain it from my previous post.






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